Conditioned Salivation Research Articles

Altered appetitive conditioning in overweight and obese women

Overweight and obese individuals show increased psychological and physiological reactivity to food cues and many of them have difficulties in achieving long-term weight loss. The current study tests whether abnormalities in the learning and extinction of appetitive responses to food cues might be responsible for this. Overweight/obese and healthy weight women completed a differential appetitive conditioning task using food as rewards, while eating expectancies, eating desires, conditioned stimulus evaluations, salivation, and electrodermal responses were assessed during an acquisition and extinction phase. Results suggested reduced discriminative conditioning in the overweight/obese group, as reflected by a worse acquisition of differential eating desires and no successful acquisition of differential evaluative responses. Some evidence was also found for impaired contingency learning in overweight and obese individuals. No group differences in conditioned salivation and skin conductance responses were found and no compelling evidence for differences in extinction was found as well. In sum, the current findings indicate that overweight and obesity may be characterized by reduced appetitive conditioning. It is suggested that this could be causally related to overeating via stronger context conditioning or a tendency towards overgeneralization in overweight and obese individuals.

Conditioned salivation and associated dreams from REM sleep.

Although research has investigated the feasibility of establishing classically conditioned physiological responses during sleep, very few experimental studies have considered whether classically conditioned cognitive associations are possible. Since dreams have previously been described as a state of “hyper-association,” an experiment involving classical conditioning of the human salivary response and associated dream content was conducted. During wakefulness, repeated pairings of a conditioned stimulus (CS; a red light) with an unconditioned stimulus (UCS; citrus juice) yielded a conditioned autonomic response (CR; salivation) on presentation of the CS alone. After exposure to the CS during REM sleep, salivary excretion rates measured upon awakening were significantly higher than measures taken from baseline REM awakenings. However, no CR-related dreams were reported by the participants. This result could be interpreted as evidence that participants in this experiment did not experience higher-order memory associations to the external stimuli presented during REM. Alternatively, the lack of CR-related dreams could be explained by previous findings that the autonomic nervous system often works independently of higher-order cognitive activity. Therefore, if an autonomic association is formed, this does not necessarily imply a cognitive one.

Inhibition of anticipatory salivation and craving in response to food stimuli

Two experiments were done to study inhibition of cue-dependent salivation and craving responses. Experiment 1 suggests that total prevention of tasting during cue exposure inhibits salivation responses to chocolate cues. On the other hand, salivation was triggered by chocolate cues after tasting a very small amount of chocolate, indicating a very robust and rapid learning of conditioned salivation responses. However, prevention of tasting during cue exposure did not affect craving, suggesting that this method cannot decrease craving or that craving is affected at different rate than salivation. Experiment 2 tested the hypothesis that tasting irrelevant food during repeated exposure to chocolate cues would inhibit anticipatory salivation and craving responses to these cues. No support for this hypothesis was observed.

Conditioned Salivation in Obese Subjects with Different Weight Kinetics

The salivation elicited by the sight of a palatable food was measured after a 16-h fast in ten non-obese females with stable body weight, seven “dynamic” obese (increasing weight) females, seven “static” obese (stable weight) females. All subjects but one gave positive salivary responses (salivation with food present minus prefood salivation). Nonobese tended to be less responsive than obese. However, the presentation of food increased saliva by 75% in dynamic obese, significantly more than in nonobese (19.1%) and static obese (26.7%); nonobese and static obese did not differ significantly. Thus the salivaty response to food, a physiological reaction linked to appetite, is increased in obese subjects gaining weight (as if they were “deprived”) and normal in static obesity (as if they normally regulated their weight at a higher level). These data lend support to the “ponderostatic theory” of obesity.

Antagonism of conditioned salivation in conscious dogs by antihypertensive drugs.

Methyldopate (methyldopa (ethyl ester)), carbidopa, clonidine, and ST-91 were evaluated for their effects on conditioned salivation in unanesthetized dogs. Clonidine produced dose-dependent inhibition of salivation 20 min after an intravenous injection. At equivalent and larger doses, ST-91, a clonidine analog which does not penetrate the blood-brain barrier, was ineffective in inhibiting conditioned salivation, suggesting that central rather than peripheral mechanisms are involved in clonidine-induced inhibition of salivation. Methyldopate also produced a dose-dependent inhibition of salivation in dogs. The mechanism involved in methyldopa-induced inhibition of salivation may involve both central and peripheral mechanisms because carbidopa, an inhibitor (like methyldopa) of peripheral aromatic decarboxylase (EC 4.1.1.28), significantly inhibited salivation.

Extinction and food-reinforced inhibition of conditioned salivation in dogs

The present experiment compared two methods of eliminating a classically conditioned response in dogs, extinction and reinforcement of nonsalivation, using both a within- and between-subjects experimental design. Eighteen dogs were trained for 16 days in Phase I, 16 days in Phase II, and 8 days in Phase III. In Phase I, each subject received classical conditioning training to two stimuli. In Phase II, Group 1 received extinction training to one stimulus and reinforcement of nonsalivation to the other stimulus. Group 2 received continued classical conditioning training to one stimulus and reinforcement on nonsalivation training to the other. Group 3 received continued classical conditioning training to one stimulus and extinction training to the other. In both the within- and between-subjects comparisons, responding to the stimulus associated with extinction was eliminated faster than responding to the stimulus associated with reinforcement of nonsalivation.

Food-reinforced inhibition of conditioned salivation in dogs.

Twelve dogs salivated to a tone that was followed by food, but not to a noise for which there was an added response dependency. The noise was followed by food if and only if they did not salivate. The addition of this response dependency vitiated the classically conditioned response to the noise. A yoked-control group of 6 dogs receiving the same sequences of stimuli and food salivated to both the tone and noise stimuli.

Posthypnotic suggestion as higher-order conditioning: a methodological and experimental analysis.

Abstract The hypothesis that hypnosis facilitates higher-order conditioning was tested. The results supported the 3 predictions made from the hypothesis: (a) The hypnosis group (N = 43) showed greater conditioning (p < .01) than the control group (N = 42); (b) the amount of conditioning for the hypnotic group was correlated with hypnotic depth (p < .01); and (c) this conditioned response, once formed, was a strong one, as evidenced by little extinction and the phenomenon of spontaneous recovery. The dependent variable, conditioned salivation, was measured by a unique procedure which allows large numbers of Ss to be measured simultaneously. The experimental design provided several innovative means for avoiding a number of shortcomings common to hypnosis experiments, including a most insidious one-the fact that most previous indicants of hypnosis have been misleading.

Some observations on the inhibition of salivation by St 155 [2-(2,5-dichlorophenylamine)-2-imidazoline hydrochloride, Catapres ®, Catapresan ®

The effects of St 155 [2-(2,6-dichlorophynylamino)-2-imidazoline hydrochloride] were investigated on conditioned salivation and pilocarpine-induced salivation in conscious dogs and on salivation caused by stimulation of the chorda tympani in anaesthetised dogs. St 155 greatly reduced conditioned salivation but did not reduce salivation produced by injecting pilocarpine or stimulating the chorda tympani. The suggestion that St 155 inhibits salivation by an action in the central nervous system is discussed. A central inhibition of salivation would account for the dryness of the mouth encountered as a side effect in the use of the drug as an antihypertensive agent.

Effects of changing the CS-US interval on human salivary responses.

ABSTRACTAn experiment was performed to test the effect of changing the CS‐US interval on the pattern of conditioned salivation. Each of 6 subjects (Ss) received 60 reinforced trials on each of 3 CS‐US intervals: 10, 20, and 40 sec. For each CS‐US interval 10 test trials were given to determine the change in pattern of response with change in the CS‐US interval. An additional session included 2 test trials in which an extraneous stimulus was given simultaneously with the CS. The results showed little evidence of inhibition of delay in the longer intervals or of disinhibition when the extraneous stimulus was applied. The most significant result was a response which followed CS offset in the 20‐ and 40‐sec intervals. The question of the nature of this response remains to be answered by use of a different experimental design. Significance of the level of conditioning remained high (p &lt;. 00001) over the manipulation of CS‐US interval.

The secretion of bromine (NaBr82, KBr82) during conditioned and unconditioned salivation.

There was less bromine in the conditioned reflex saliva than in the unconditioned one in 8 dogs (with different types of the nervous activity) in an hour in 2, 3 and 4 days after the intravenous injection of NaBr82 or KBr82. Consequently, a rise of the iodine content in the conditioned secretion in comparison with the unconditioned one (6) was not connected with the peculiar properties of the haloids. A suggestion is made on the possible mechanisms determining different saliva bromine content in conditioned and unconditioned reflexes. Blood and saliva bromine level in the unconditioned secretion were compared in 2, 3, 5, 10, 15, 20, 30, 45, 60, 90 minutes, 2, 3, 8 hours and on the 2nd and the following days after the injection. The maximum salivary level was reached within the first 10 minutes. Then a gradual reduction was noted. Salivary concentration was usually greater than that in the blood.

Toxicology of benzalkonium chloride given orally in milk or water to rats and dogs

Benzalkonium chloride was well tolerated by male albino rats when administered orally in single daily doses of 50.0 mg/kg in milk or water for 12 weeks, or to beagle dogs in doses of 12.5 mg/kg in milk or water for one year. Slight depression of body weight gain was observed in rats given 100.0 mg/kg in water, but no depression occurred at the same dose in milk. No gross or histologic changes were observed in the tissues of these rats. Several dogs died that were medicated at 25.0 or 50.0 mg/kg in water, whereas none died when the milk vehicle was used. Conditioned salivation, vomiting, and enteritis were frequently observed in the dogs. The severity of these signs was directly related to the dosage and was more intense with the water than with the milk vehicle. The data from this presentation and those of Fitzhugh and Nelson (1948) and Alfredson et al. (1951) indicate that benzalkonium chloride was well tolerated at dose levels much higher than the recommended sanitary use concentrations of benzalkonium chloride when the data are compared on a calculated dose for dose basis (dietary vs. stomach tube).

On the ratio of conditioned and unconditioned saliva secretion on well-formed conditioned reflexes

For the formation of conditioned reflexes, as is known, the coincidence of the conditioned stimulus in time with the unconditioned one, for example, with food, is required. If reflexes have already been formed, that is, the food reaction in children opening the mouth and the separation of saliva appears after the onset of the action of the conditioned stimulus, then in order for them not to fade away, the action of the conditioned stimulus must be reinforced by giving some food substance, which causes child a series of chewing movements and increased salivation, unconditioned secretion of saliva. Thus, in our experiments, we have the opportunity to take into account the values ​​of both conditioned and unconditioned salivation and their relationship to each other. As is known, a conditioned secretory reaction is composed of several moments: the energy from a conditioned external stimulus is transformed into a nervous process of irritation, which captures a certain group of cells of a particular analyzer in the cerebral cortex. Then this irritation is carried out, apparently, to the food center and further to the centers of salivation, which cause the salivary glands to function. The intensity of conditioned salivation depends, therefore, on the excitability of the cells of the cerebral hemispheres and further on the food center. If the conditioned stimulus evokes a weak stimulus process in the corresponding part of the cortex, then it is clear that the conditioned secretion of saliva is also low. A decrease in the excitability of the food center also leads to a significant weakening of conditioned reflex activity.

Comparison Between Morphine and Feeding as Agents in Production of Conditioned Salivary Response.

In a quantitative study of the conditioned salivation in the dog developed through daily injections of morphine it was found that the flow of saliva was unusually copious. Thus the total quantity of saliva secreted conditionally by a 12 to 14 kilo dog would run as high as 400 cc. in one hour. The conditioned stimulus in this case consisted in placing the dog in a stand where it remained for a definite period of time (usually 30 minutes), before receiving a subcutaneous injection of morphine. In the work of Pavlov and others where food or acid was employed as an unconditioned stimulus, the “delay” between the beginning of the action of the conditioned stimulus and the application of the unconditioned stimulus was a matter of 2 to 3 minutes or even less. This suggested the possibility that the long “delay” employed in the case of the morphine-produced response might be responsible for the large amounts of saliva secreted. To test this, 3 dogs, with fistulae of the submaxillary glands, were placed in a stand for 30 minutes daily, for periods of 22, 27, and 76 days respectively. Each day, at the end of the 30 minutes in the stand, they were fed a meal of ground beef heart. The unconditioned salivary response to feeding was greater than to the injection of morphine (3-6 cc. compared to 1-3 cc.), but none of the 3 dogs showed any conditioned secretion before feeding. All these dogs developed the conditioned salivary response to morphine on subsequent occasions in the course of a few days. It seems that in the development of conditioned salivation, using the same conditioned stimulus, daily injections of morphine are efficacious, whereas daily feeding is not.